ALSA: seq-dummy: remove deadlock-causing events on close (0767e95b) · Commits · 戴 / test

When the last subscriber to a "Through" port has been removed, the subscribed destination ports might still be active, so it would be wrong to send "all sounds off" and "reset controller" events to them. The proper place for such a shutdown would be the closing of the actual MIDI port (and close_substream() in rawmidi.c already can do this). This also fixes a deadlock when dummy_unuse() tries to send events to its own port that is already locked because it is being freed. Reported-by:

Peter Billam <peter@www.pjb.com.au> Cc: <stable@vger.kernel.org> Signed-off-by:

Clemens Ladisch <clemens@ladisch.de> Signed-off-by:

Takashi Iwai <tiwai@suse.de>

sound/core/seq/seq_dummy.c

+0 −31

Original line number	Diff line number	Diff line
		@@ -81,36 +81,6 @@ struct snd_seq_dummy_port {

		static int my_client = -1;

		/*
		* unuse callback - send ALL_SOUNDS_OFF and RESET_CONTROLLERS events
		* to subscribers.
		* Note: this callback is called only after all subscribers are removed.
		*/
		static int
		dummy_unuse(void private_data, struct snd_seq_port_subscribe info)
		{
		struct snd_seq_dummy_port *p;
		int i;
		struct snd_seq_event ev;

		p = private_data;
		memset(&ev, 0, sizeof(ev));
		if (p->duplex)
		ev.source.port = p->connect;
		else
		ev.source.port = p->port;
		ev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
		ev.type = SNDRV_SEQ_EVENT_CONTROLLER;
		for (i = 0; i < 16; i++) {
		ev.data.control.channel = i;
		ev.data.control.param = MIDI_CTL_ALL_SOUNDS_OFF;
		snd_seq_kernel_client_dispatch(p->client, &ev, 0, 0);
		ev.data.control.param = MIDI_CTL_RESET_CONTROLLERS;
		snd_seq_kernel_client_dispatch(p->client, &ev, 0, 0);
		}
		return 0;
		}

		/*
		* event input callback - just redirect events to subscribers
		*/
		@@ -175,7 +145,6 @@ create_port(int idx, int type)
		\| SNDRV_SEQ_PORT_TYPE_PORT;
		memset(&pcb, 0, sizeof(pcb));
		pcb.owner = THIS_MODULE;
		pcb.unuse = dummy_unuse;
		pcb.event_input = dummy_input;
		pcb.private_free = dummy_free;
		pcb.private_data = rec;

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